Coccygeal fractures are generally low-severity injuries, which nonetheless can be diagnostically challenging. Diagnosis may be delayed or missed due to coccygeal anatomy and patient/technical factors (e.g. obesity, overlying bowel gas/feces).
Given that management of coccygeal fractures is nea...
The coccygeus muscle, also known as the ischiococcygeus muscle, is a remnant muscle of the pelvic floor.
The coccygeus is a paired muscle which is triangular in shape and overlies the sacrospinous ligament. The coccygeus lies parallel to the inferior border of the piriformis musc...
The coccyx (plural: coccyges) is the series of rudimentary vertebrae forming the caudal termination of the vertebral column and is positioned inferior to the apex of the sacrum. The coccyx is one leg of the tripod formed in conjunction with the ischial tuberosities for support in a seated positi...
The coccyx anteroposterior (AP) view is used to demonstrate the coccyx, in conjunction with the sacrum and coccyx (lateral view). Follow departmental protocol in relation to imaging this region.
This projection helps to visualize pathology of the coccyx, especially fractures. To m...
There are several described cockade signs in radiology:
cockade sign (intraosseous lipoma)
cockade sign (aorto-left ventricular tunnel) 1
cockade sign (appendicitis) 2
cockade sign (hypertrophic pyloric stenosis) 3
cockade sign (GI tumors) 4
The cockade sign describes the classic appearance of a calcaneal intraosseous lipoma seen as a well-defined lytic lesion with a central calcification.
History and etymology
It is named after a cockade, which is a badge, usually in the form of a rosette or knot, generally worn on the hat.
A Codman triangle is a type of periosteal reaction seen with aggressive bone lesions. The periosteum does not have time to ossify with shells of new bone (e.g. as seen in a single layer and multilayered periosteal reaction) in aggressive lesions, so only the edge of the raised periosteum will os...
COL4A1-related disorders are a group of autosomal dominant disorders caused by a mutation in the COL4A1 gene.
The exact prevalence is unknown, but the group of disorders is considered to be under-recognized, especially asymptomatic variants 1.
The clinical ...
The collateral ligaments of the foot are attached to the dorsal tubercles on the metatarsal heads and the corresponding side of the phalangeal bases.
Colles fractures are very common extra-articular fractures of the distal radius that occur as the result of a fall onto an outstretched hand. They consist of a fracture of the distal radial metaphyseal region with dorsal angulation and impaction, but without the involvement of the articular surf...
Comminuted fractures are fractures where more than 2 bone components are created.
The problem with the term is that it includes a very heterogeneous group of fractures from a 3 part humeral head fracture to a multi-part fracture of the femur following a high-energy road traffic accident.
The common peroneal nerve, also known as common fibular nerve, forms the lateral part of the sciatic nerve and supplies the leg.
origin: one of two terminal branches of the sciatic nerve
course: diverges laterally to enter the lateral compartment of the leg
Common peroneal neuropathy, also known as fibular neuropathy, is a condition characterized by damage or compression of the common peroneal nerve (CPN) at the level of the fibular head. It is the most common cause of spontaneous painless foot drop.
spontaneous painless fo...
Companion shadows are smooth, homogeneous, radiopaque shadows running parallel along the bones. In a study of 700 chest radiographs, Ben Felson found that 75% had companion shadows on the lower ribs 3.
They appear secondary to soft tissues and intercostal muscles running ...
Complete fractures are fractures where the parts of the bone that have been fractured are completely separated from each other. There is complete separation of the cortex circumferentially.
Complete fractures can be classified as:
transverse: straight across the bone
oblique: oblique line acr...
Complex meniscal tears extend in more than one plane, and can in turn create separate flaps of meniscus.
The mensical tear usually includes a combination of radial, horizontal, and longitudinal components (any two or all three). Often the meniscus substance app...
Complex regional pain syndrome (CRPS), also known as Sudeck atrophy, is a condition which can affect the extremities in a wide clinical spectrum. CRPS is principally a clinical diagnosis seen more commonly in females than males with a mean age of presentation of 50 to 70 years 12. No one imaging...
Complications of total hip arthroplasty are common and it is essential for the radiologist to be aware of them in the assessment of radiographs of total hip replacements. Complications are many and can occur at various time intervals following the initial surgery:
aseptic loosening: considered ...
Composite hemangioendotheliomas are locally aggressive and rarely metastasizing vascular tumors consisting of different and histologically distinct elements.
Composite hemangioendotheliomas are very rare and mostly seen in adults. Women are slightly more commonly affected 1,2.
The comprehensive arthroscopic management (CAM) procedure of the shoulder is an arthroscopic joint-preserving technique in the surgical management glenohumeral osteoarthritis.
The comprehensive arthroscopic management was first described by Millet et al. 2010 1.
Computed bone age measurement refers to the automatic computer analysis of a left hand radiograph in order to estimate accurately bone age in cases of suspected growth delay.
Advanced digital processing of data from automatic computer analysis of the phalangeal/carpal bones and/or ep...
Computed tomography scanogram for leg length discrepancy assessment is performed in patients (children in most of the cases) with suspected inequality in leg length (anisomelia).
obtained images are typically anteroposterior (AP) scout views of the bilateral femurs and tibias
There are many conditions that can involve both skin and bone.
osteolytic bone lesions
basal cell nevus syndrome
langerhans cell histiocytosis
Condylar process fractures are fractures of the condylar process of the mandible. The condylar process of the mandible is involved in around 30% of all mandibular fractures.
Condylar fractures are classified according to the location of the fracture and the direction displacement of the condyle...
The condyle-C1 interval (CCI) is the measurement of the interval between condyle and C1 at four equidistant points on the joint surface in sagittal and coronal reconstructions of computed tomography.
The CCI is reported to have a high lateral symmetry in children 1. Used with a cut-off of 4 mm,...
Condyloid joints are a type of synovial joint where the articular surface of one bone has an ovoid convexity sitting within an ellipsoidal cavity of the other bone.
Condyloid joints allow movement with two degrees of freedom much like saddle joints. They allow flexion/extension, ab...
Congenital absence of a spine pedicle is a rare congenital condition, but awareness of its characteristic imaging appearance is important to avoid misdiagnosis.
Failure to recognize this entity can lead to misdiagnosis of unilateral facet subluxation/dislocation, leading to unnecessary treatmen...
Congenital absence of the cruciate ligaments is a rare condition, most of the knowledge being collated from case reports.
Its prevalence is reported at 0.017 per 1000 live births 1,5.
The following features may also be present 2,3,5:
lateral femoral condyle hypopl...
Congenital anomalies of the posterior arch of the atlas (C1) are relatively common anomalies. They may range from partial defects presenting as clefts to complete absence of the posterior arch (aplasia).
These anomalies are classified according to Currarino (see below). It should not be confuse...
Congenital diaphragmatic herniation (CDH) accounts for a small proportion of all diaphragmatic herniae. However, it is one of the most common non-cardiac fetal intrathoracic anomalies.
Congenital diaphragmatic hernias are seen in 1 of every 2000-4000 live births. 84% are left-side...
Congenital insensitivity to pain (CIP) refers to a group of rare hereditary sensory and autonomic neuropathies (HSANs) characterized by an inability to feel pain 1.
Although not clearly defined in the literature, congenital insensitivity to pain is not one specific diagnosis but de...
Congenital limb amputation is the absence of a fetal limb or part of a limb that usually occurs due to disruption of vascular supply.
Congenital amputations occur in 0.5 (range 0.03-1) per 1000 live births 2.
They are slightly more common in the upper limb (60%) than ...
Congenital lumbar spinal stenosis is a type of spinal canal stenosis and has different epidemiology with less severe degenerative change compared to acquired/degenerative lumbar spinal stenosis.
Congenital lumbar spinal stenosis tends to affect patients at a younger age (30-50 ye...
Congenital muscular dystrophies are a heterogeneous group of autosomal recessive myopathies presenting at birth with hypotonia, delayed motor development, and early onset of progressive muscle weakness, confirmed with a dystrophic pattern on muscle biopsy.
There is a wid...
Congenital pseudoarthrosis of the clavicle is a rare condition, which typically presents as an isolated anatomical variant.
Usually presents as a midclavicular swelling in the neonate or young child 1.
Congenital pseudoarthrosis of the clavicle is more commo...
Congenital pseudoarthrosis of the tibia describes abnormal bowing that can progress to a segment of bone loss simulating the appearance of a joint. The condition is usually apparent shortly after birth and is rarely diagnosed after the age of two.
The etiology is unclear, however, ar...
Congenital radial head dislocation is the most common congenital elbow abnormality. It can occur in isolation, or more commonly may be associated with other conditions or syndromes.
Overall, congenital radial head dislocation is rare 2.
Congenital radial he...
Congenital talipes equinovarus is considered the most common anomaly affecting the feet diagnosed on antenatal ultrasound.
While some use talipes equinovarus and clubfoot synonymously, in certain publications, the term clubfoot is considered a more general descriptive term that des...
Congenital hallux valgus is a very rare finding wherein a fetus or newborn shows lateral deviation of the first toe(s). When found on prenatal imaging, bilateral congenital/foetal hallux valgus is highly suggestive of fibrodysplasia ossificans progressiva 1,2.
The connective tissue diseases or disorders (CTDs), also known as collagen vascular diseases, form a large heterogeneous group of conditions that are linked by a disease process that primarily involves the connective soft tissues of the body and often the vasculature too, due to shared structura...
The Connolly procedure is performed by an open posterior approach and involves transferring the infraspinatus with a portion of greater tuberosity into the defect, rendering the defect extra-articular; although this procedure restores the stability, it reduces the shoulder range of movement. The...
The conoid ligament is one of two components forming the coracoclavicular (CC) ligament. The trapezoid ligament is the other component.
The conoid ligament takes the shape of an inverted cone. It is the posteromedial part of the coracoclavicular ligament. Its apex originates from...
The conoid tubercle also known as the coracoid tuberosity (not to be confused with the coracoid process of the scapula) is a bony prominence on the inferior surface of the lateral third of the clavicle.
It marks the insertion of the conoid ligament (which along with the trapezoid ligament) for...
A useful mnemonic to remember the contents of the cubital fossa is, from medial to lateral:
My Brother Throws Rad Parties
M: median nerve
B: brachial artery
T: tendon of biceps
R: radial nerve
P: posterior interosseous branch of radial nerve
Contiguous bone activity is a bone scan phenomenon seen in tumors which incite a regional hyperemia. Increased activity on blood pool images is seen extending across joints and to adjacent bones. This should not be mistaken for direct tumor involvement.
An example of a tumor which may demonstr...
Contrast media extravasation (CMEV) refers to the leakage of intravenously-administered contrast media from the normal intravascular compartment into surrounding soft tissues; it is a well-known complication of contrast-enhanced CT scanning. It can also occur in MRI studies, but the complication...
A contrecoup injury of the knee is a bone contusion of the posterior lip of the medial tibial plateau. It occurs during knee reduction after a pivot shift injury and is highly associated with ACL tears 1, and peripheral tear or meniscocapsular separation of the medial meniscus posterior horn 2.
Conus medullaris syndrome is caused by an injury or insult to the conus medullaris and lumbar nerve roots. It is a clinical subset of spinal cord injury syndromes. Injuries at the level of T12 to L2 vertebrae are most likely to result in conus medullaris syndrome.
Conventional chondrosarcoma also known as central chondrosarcoma is the most common subtype of chondrosarcoma and may be low, intermediate or high grade (see chondrosarcoma grading).
They typically occur in the 4th and 5th decades with a slight male predominance 1.5-2:1.
Convolutional markings are normal impressions of the gyri on the inner table of the skull. They appear during times when the brain is growing rapidly, typically between the ages of 3 and 7 years of age 4. They are seen predominantly posteriorly.
If they are pronounced and over the more anterio...
The Cooke and Newman classification of periprosthetic hip fractures is a modification of the Bethea classification proposed several years earlier.
explosion type fracture, comminuted around the stem of the implant
the prosthesis is always loose and the fracture is inherently unstable
Cookie bite metastases are characterized by small focal eccentric lytic external cortical destruction in long tubular bones. This type of destruction is typically described for metastases from lung cancer; however, they can also occur with other tumors.
Copper beaten skull, also known as beaten silver skull or beaten brass skull, refers to the prominence of convolutional markings (gyral impressions on the inner table of the skull) seen throughout the skull vault.
The appearance of a copper beaten skull is associated with...
Coracoacromial arch is a term for different bony and ligamentous structures, which form the superior border supraspinatus outlet.
It comprises the following anatomical structures from anterior to posterior 1:
The coracoacromial ligament is a flat triangular band that plays a supportive role for the shoulder joint.
originates from the medial border of the acromion
attaches to the lateral border of the coracoid process
overlies the subacromial bursa
indirectly supports the head of th...
The coracobrachialis muscle is one of the three muscles of the anterior compartment of the arm. It sits beneath the biceps brachii, inserting via a flat tendon into the medial shaft of the humerus.
origin: coracoid process of scapula
insertion: via a flat tendon onto the midportion of the medi...
The coracoclavicular bursa, also known as the supracoracoid bursa, can be found within the angle separating the trapezoid and conoid segments of the coracoclavicular ligament 1,3. It is surrounded by varying amounts of fibro-fatty tissue. Smaller bursae associated with the coracoid process or ei...
The coracoclavicular (CC) distance is an indicator of the integrity of the coracoclavicular (CC) ligament.
The CC distance is assessed on frontal radiography of the shoulder or clavicle or the coronal projection of a CT or MRI as the distance between the superior cortex of the cora...
The coracoclavicular joint is a normal variant of the pectoral girdle, where the conoid tubercle of the clavicle appears enlarged or elongated, with a flattened inferior surface where it approximates the coracoid process of the scapula to form an articulation.
More common in Asia...
The coracoclavicular (CC) ligament is the major vertical stabilizing factor of the acromioclavicular joint.
The coracoclavicular ligament can be divided into two parts, the more medial conoid ligament and trapezoid ligament.
origin: knuckle of the coracoid proc...
Coracoclavicular (CC) ligament injury is common with shoulder trauma. It is considered part of the spectrum of acromioclavicular joint injuries 2 and is not often an isolated injury. It is also often injured with clavicular fractures.
This injury is easy to miss, especially with the presence o...
The coracohumeral interval is usually measured on axial or oblique sagittal CT or MRI and normally measures between 7-11 mm. A measurement <6 mm is always considered abnormal 1.
The coracohumeral ligament (CHL) is a strong supportive ligament of the shoulder joint and is a part of the rotator cuff interval.
originates from the lateral surface of the base of the coracoid process
runs laterally across the glenohumeral capsule and covers the long head of t...
The coracoid process is an anteriorly projecting hook-like process on the superolateral edge of the scapula that projects anterolaterally.
coracobrachialis from the medial apex
short head of biceps brachii from the lateral apex
pectoralis minor from the m...
Coracoid process fractures are an uncommon type of scapular fracture. They do not often occur in isolation and are often associated with acromial, clavicular, or other scapular fracture, as well as glenohumeral dislocation or acromioclavicular joint injury.
Coracoid fractures repr...
The corduroy sign refers to vertically-oriented, thickened trabeculae seen in intraosseous hemangiomas of the spine. It is the sagittal/coronal equivalent of the polka-dot sign seen on axial imaging.
It is caused by the replacement of the normal cancellous bone by thickened vertical trabeculae...
Coronal balance is one of the features that needs to be assessed on long spine radiographs obtained for spinal deformity, particularly scoliosis. It measures whether or not the upper spine is located over the midline (normal) or off to one side.
To assess coronal balance, a vertic...
Coronal vertebral clefts refer to the presence of radiolucent vertical defects on a lateral radiograph.
It is most often seen in premature male infants 1,3. As they can occur as part of normal variation (especially in the lower thoracic-upper lumbar spine of premature infants) t...
Coronoid process can refer to a number of different anatomical structures:
coronoid process (mandible)
coronoid process (ulna)
Fractures of the coronoid process of the ulna are uncommon and often occur in association with elbow dislocation.
Fracture of the coronoid process is thought to result from elbow hyperextension with either avulsion of the brachialis tendon insertion or shearing off by the...
Corpectomy (followed by fusion) refers to the removal of one or more vertebral bodies to treat compressive myelopathy caused by extensive hypertrophic osteoarthritis, tumor, infection or severe trauma. In most cases, the intervertebral discs are removed as well 1-3.
An anterior or p...
The corrugator supercilii muscles are two small, triangular muscles of facial expression, which contribute to movement of the eyebrows, including frowning. They are located deep to the frontal part of occipitofrontalis and orbicularis oculi muscles, with which they blend 2.
The outer shell of compact bone is called cortical bone or cortex. It is formed by compact bone which is one of the two macroscopic forms of bone, the other being cancellous bone.
Cortical bone contains Haversian systems (osteons) which contain a central Haversian canal surround...
Cortical desmoids, also known as cortical avulsive injuries, Bufkin lesion or distal cortical femoral defects/irregularities, are a benign self-limiting entity that are common incidental findings. This is a classic "do not touch" lesion, and should not be confused with an aggressive cortical/per...
Costal cartilage fractures are fractures of the cartilage connecting the ribs anteriorly to the sternum.
There is little published data on costal cartilage fractures. Most reported cases are in males and resulted from blunt trauma or a fall 1,2.
In young ch...
The costochondral joints are the joints between each rib and its costal cartilage. They are primary cartilaginous joints. These joints represent the demarcation of the unossified and ossified part of the rib 1. The joint is held together by periosteum, with the lateral aspect of the costal ca...
The costoclavicular ligament or rhomboid ligament (a.k.a. Halsted's ligament 2) is the major stabilizing factor of the sternoclavicular joint and is the axis of movement of the joint.
The costoclavicular ligament binds the inferior medial clavicle (via the rhomboid fossa) to the ...
The costovertebral joint is the articulations between the ribs and the vertebral column.
The ribs articulate with the thoracic vertebrae via two distinctly different joints:
costovertebral joint - articulation between the head of the rib and the vertebral body
The costoxiphoid ligaments, also known as the chondroxiphoid ligaments, are inconstant fibrous structures joining the anterior and posterior surfaces of the xiphoid to the respective surfaces of the adjacent seventh and, occasionally, sixth costal cartilages.
The cotton wool appearance is a plain film sign of Paget disease and results from thickened, disorganized trabeculae which lead to areas of sclerosis in a previously lucent area of bone, typically the skull. These sclerotic patches are poorly defined and fluffy.
Other Paget disease re...
The Coughlin classification is the most widely used to type bunionettes. It relies on simple angle measurements on weight-bearing foot radiographs taken in the dorsoplantar projection 1,2. In 2013 DiDomenico et al added type IV 2.
type I: enlarged lateral surface of the head of ...
Cowden syndrome, also known as multiple hamartoma syndrome, is characterized by multiple hamartomas throughout the body and increased risk of several cancers.
Type 2 segmental Cowden syndrome is the association of Cowden syndrome with a Cowden nevus when it is considered a type of ...
Coxa magna is the asymmetrical, circumferential enlargement and deformation of the femoral head and neck. Definitions in the literature vary but enlargement with asymmetry >10% in size is a reasonable cut-off for diagnosis 1.
Coxa plana is flattening of the femoral head epiphysis and is associated with many skeletal disorders:
multiple epiphyseal dysplasia
hemoglobinopathies, e.g. sickle cell anemi...
Coxa profunda refers to a deep acetabular socket. On pelvis x-rays it is seen as the acetabular fossa being medial to the ilioischial line. It should be differentiated from protrusio acetabuli, where the femoral head is seen additionally medial to the ilioischial (Kohler's) line. Coxa profunda i...
Coxa valga describes a deformity of the hip where there is an increased angle between the femoral neck and femoral shaft.
Coxa valga is often associated with shallow acetabular angles and femoral head subluxation.
neuromuscular disorders, e.g. cerebral palsy
Coxa vara describes a deformity of the hip where the femoral neck-shaft angle is decreased, usually defined as less than 120 degrees.
It can be congenital or acquired. The common mechanism in congenital cases is a failure of medial growth of the physeal plate 3.
Cozen fracture or phenomenon is the valgus angulation deformity of the tibia following a proximal tibial metaphyseal fracture in children.
This typically occurs as a late deformity in children aged 3-6 years.
Proposed causes include:
non-recognized or under ...
Craniofacial fibrous dysplasia is one of four types of fibrous dysplasia and is characterized, as the name suggests, by involvement of the skull and facial bones.
For a general discussion of the underlying pathology, refer to the parent article fibrous dysplasia.
Although the term...
Craniosynostosis refers to the premature closure of the cranial sutures. The skull shape then undergoes characteristic changes depending on which suture(s) close early.
There is a 3:1 male predominance with an overall incidence of 1 in 2000-2500. 8% of cases are syndromic or famil...
Craniotabes is defined as a softening of the skull bones that may be normally present in newborns.
Craniovertebral junction (CVJ) anomalies can be congenital, developmental or due to malformation secondary to any acquired disease process. These anomalies can lead to cranial nerve compression, vertebral artery compression, and obstructive hydrocephalus.
The craniovertebral junction...
Creatine kinase (CK), also known as creatine phosphokinase (CPK), is a key enzyme, for energy production in mitochondria and muscle tissues. It is important as a diagnostic assay in clinical practice, primarily because inflamed/injured muscle releases creatine kinase into the circulation 1.